Flexible tubular portion of endoscope and endoscope having this flexible tubular portion

ABSTRACT

A flexible tubular portion of an endoscope includes a spiral tube portion. The spiral tube portion includes a closely wound portion to at least a part of which an initial tension is applied, and a sparsely wound portion provided at least at one end of the closely wound portion.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation Application of PCT Application No.PCT/JP2012/078374, filed Nov. 1, 2012 and based upon and claiming thebenefit of priority from prior Japanese Patent Application No.2011-242704, filed Nov. 4, 2011, the entire contents of all of which areincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a flexible tubular portion of anendoscope, and an endoscope having the flexible tubular portion.

2. Description of the Related Art

In general, an endoscope has a flexible tubular portion. A flexibletubular portion is disclosed in, for example, Jpn. Pat. Appln. KOKAIPublication No. 11-285469. The flexible tubular portion includes, forexample, a metallic spiral tube portion, a mesh tube portion which isprovided outside the spiral tube portion and which covers the spiraltube portion, and an outer tube which is provided outside the mesh tubeportion and which covers the mesh tube portion. The mesh tube portion isstacked on the spiral tube portion, and the outer tube is stacked on themesh tube portion. Thus, the flexible tubular portion has a three-layerstructure.

The flexible tubular portion has a flexibility, and is therefore flexed,for example, when a load is applied thereto. In this case, the load isproportional to the flexing amount (deformation amount), and the flexingamount is greater when the load is higher. This load is, for example, anexternal pressure received from the intestines when the flexible tubularportion is inserted into the large intestine and abuts on a flectionsuch as the sigmoid colon in the large intestine.

BRIEF SUMMARY OF THE INVENTION

According to one aspect of a flexible tubular portion of an endoscope ofthe present invention, there is provided the flexible tubular portion ofan endoscope including a spiral tube portion, wherein the spiral tubeportion comprises a closely wound portion to at least a part of which aninitial tension is applied, and a sparsely wound portion provided atleast at one end of the closely wound portion.

According to one aspect of the present invention, there is provided anendoscope comprising the above-mentioned flexible tubular portion of theendoscope.

Advantages of the invention will be set forth in the description whichfollows, and in part will be obvious from the description, or may belearned by practice of the invention. Advantages of the invention may berealized and obtained by means of the instrumentalities and combinationsparticularly pointed out hereinafter.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate embodiments of the invention, andtogether with the general description given above and the detaileddescription of the embodiments given below, serve to explain theprinciples of the invention.

FIG. 1 is a schematic diagram of an endoscope according to the presentinvention;

FIG. 2 is a diagram showing a three-layer structure of a flexibletubular portion;

FIG. 3A is a diagram showing a spiral tube portion (closely woundportion) to which an initial tension is applied;

FIG. 3B is a diagram showing how to measure the initial tension;

FIG. 3C is a diagram showing a general spiral tube portion which isformed by molding a belt-shaped thin plate material into a spiral shape;

FIG. 3D is a diagram showing how the closely wound portion is flexed bythe application of a load equal to or more than the initial tension fromthe state shown in FIG. 3A;

FIG. 4 is a graph showing the relation between the load and the flexingamount in the closely wound portion and the general spiral tube portion;

FIG. 5A is a diagram showing the relation between the length of thespiral tube portion, the length of a sparsely wound portion, and thelength of the closely wound portion in a straight state;

FIG. 5B is a diagram showing the relation between the length of thespiral tube portion, the length of the sparsely wound portion, and thelength of the closely wound portion in a bent state;

FIG. 6A is a diagram showing a first modification in the arrangement ofthe closely wound portion and the sparsely wound portion;

FIG. 6B is a diagram showing a second modification in the arrangement ofthe closely wound portion and the sparsely wound portions;

FIG. 6C is a diagram showing the change in the number of turns of theclosely wound portion;

FIG. 7A is a diagram showing a first modification of the sectional shapeof a wire in the closely wound portion;

FIG. 7B is a diagram showing a second modification of the sectionalshape of the wire in the closely wound portion; and

FIG. 7C is a diagram showing a third modification of the sectional shapeof the wire in the closely wound portion.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, embodiments of the present invention will be described indetail with reference to the drawings.

First Embodiment

[Configuration]

A first embodiment is described with reference to FIG. 1, FIG. 2, FIG.3A, FIG. 3B, FIG. 3C, FIG. 3D, FIG. 4, FIG. 5A, and FIG. 5B.

[Endoscope 1]

As shown in FIG. 1, an endoscope 1 has an elongated insertion portion 10to be inserted into, for example, a body cavity of a patient, and anoperation portion 60 which is coupled to a proximal end portion of theinsertion portion 10 and which operates the endoscope 1.

[Insertion Portion 10]

The insertion portion 10 has a distal hard portion 21, a bending portion23, and a flexible tubular portion 25 in order from a distal end portionside of the insertion portion 10 to the proximal end portion side of theinsertion portion 10. A proximal end portion of the distal hard portion21 is coupled to a distal end portion of the bending portion 23. Aproximal end portion of the bending portion 23 is coupled to a distalend portion of the flexible tubular portion 25.

The distal hard portion 21 is the distal end portion of the insertionportion 10, and is hard and unbendable.

The bending portion 23 is bent in a desired direction, for example, invertical and horizontal directions by the operation of a bendingoperation portion 67 described later. When the bending portion 23 isbent, a position and direction of the distal hard portion 21 change, anobservation target is illuminated by illumination light, and theobservation target is caught in an observation field.

The flexible tubular portion 25 has desired flexibility. Thus, theflexible tubular portion 25 is flexed by external force. The flexibletubular portion 25 is a tubular member extending from a later-describedmain body portion 61 in the operation portion 60. The structure of theflexible tubular portion 25 will be described later.

[Operation Portion 60]

The operation portion 60 has the main body portion 61 from which theflexible tubular portion 25 extends, a grasp portion 63 which is coupledto a proximal end portion of the main body portion 61 and which isgrasped by an operator who operates the endoscope 1, and a universalcord 65 connected to the grasp portion 63.

[Grasp Portion 63]

The grasp portion 63 has the bending operation portion 67 which isoperated to bend the bending portion 23. The bending operation portion67 has a horizontal bending operation knob 67 a which is operated tohorizontally bend the bending portion 23, and a vertical bendingoperation knob 67 b which is operated to vertically bend the bendingportion 23, and a fixing knob 67 c which fixes the position of the bentbending portion 23.

The grasp portion 63 also has a switch portion 69. The switch portion 69has a suction switch 69 a and an air/water supply switch 69 b. Theswitch portion 69 is operated by the hand of the operator when the graspportion 63 is grasped by the operator. The suction switch 69 a isoperated when the endoscope 1 sucks, for example, mucus or fluid from anunshown suction opening portion provided in the distal hard portion 21via an unshown suction channel. The air/water supply switch 69 b isoperated when the fluid is supplied from an unshown air/water supplychannel to secure an observation field of an unshown imaging unit in thedistal hard portion 21. The fluid includes liquid and gases.

The grasp portion 63 has various buttons 71 for endoscopic photography.

[Universal Cord 65]

The universal cord 65 has a connection portion 65 a to be connected toan unshown video processor or a light source device.

[Flexible Tubular Portion 25]

Now, the structure of the flexible tubular portion 25 is described withreference to FIG. 1 and FIG. 2.

The flexible tubular portion 25 has, for example, a hollow shape. Morespecifically, as shown in FIG. 2, the flexible tubular portion 25 has,for example, a spiral tube portion 31, a mesh tube portion 41 which isprovided outside the spiral tube portion 31 and which covers the outercircumferential surface of the spiral tube portion 31, and an outer tube51 which is provided outside the mesh tube portion 41 and which coversthe outer circumferential surface of the mesh tube portion 41. The meshtube portion 41 is stacked on the spiral tube portion 31, and the outertube 51 is stacked on the mesh tube portion 41.

Thus, the flexible tubular portion 25 is composed of the spiral tubeportion 31, the mesh tube portion 41, and the outer tube 51 so that theflexible tubular portion 25 has a three-layer structure. A diameter ofthe flexible tubular portion 25 is, for example, 12 mm.

[Spiral Tube Portion 31]

The spiral tube portion 31 according to the present embodiment is aspiral elastic tube member having resilient force. This resilient forceincludes, for example, a rebound property, impact resilience,hysteresis, and spring characteristics, and has the property ofrestoring the bent spiral tube portion 31 to a substantially straightstate. The spiral tube portion 31 is formed into the shape of a coilpipe. As shown in FIG. 2 and FIG. 3A, the spiral tube portion 31integrally has a closely wound portion 32 to which an initial tension isapplied, and a sparsely wound portions 33 provided in both end of theclosely wound portion 32. Since the spiral tube portion 31 has theresilient force, the closely wound portion 32 is configured as, forexample, a closely coil spring, and the sparsely wound portions 33 areconfigured as, for example, sparsely wound coil springs. The closelywound portion 32 is, for example, a closely wound coil. The sparselywound portions 33 are, for example, sparsely wound coils. The initialtension is applied along a longitudinal axis direction of the closelywound portion 32.

As shown in FIG. 2 and FIG. 3A, the closely wound portion 32 has adistal end portion 32 a and a proximal end portion 32 b. The distal endportion 32 a is connected to one sparsely wound portion 33 a, and theproximal end portion 32 b is connected to the other sparsely woundportion 33 b. Thus, the closely wound portion 32 is held between thesparsely wound portions 33 in a axial direction of the spiral tubeportion 31, and is adjoined to the sparsely wound portions 33 at thedistal end portion 32 a and the proximal end portion 32 b. Therefore, inthe present embodiment, in the axial direction of the spiral tubeportion 31, the spiral tube portion 31 has the sparsely wound portion 33a, the closely wound portion 32, and the sparsely wound portion 33 b inorder from a distal end portion 31 g of the spiral tube portion 31 (theflexible tubular portion 25) to a proximal end portion 31 h of thespiral tube portion 31 (the flexible tubular portion 25).

The closely wound portion 32 and the sparsely wound portions 33 arespiral wire rods formed by a spiral wire 31 b. The closely wound portion32 and the sparsely wound portions 33 are formed as one by the same wire31 b.

The closely wound portion 32 is formed so that the wires 31 b adjacentin the axial direction of the spiral tube portion 31 are brought intoclose contact with each other without space therebetween by theabove-mentioned initial tension. That is, in the closely wound portion32, the wires 31 b are in close contact with each other in the axialdirection of the spiral tube portion 31.

In contrast, in the sparsely wound portion 33 to which the initialtension is not applied, the sparsely wound portion 33 is formed so thatthe wires 31 b are provided apart from each other in the axial directionof the spiral tube portion 31 to have space in the axial direction ofthe spiral tube portion 31. That is, in the sparsely wound portion 33,the wires 31 b are not in close contact with each other in the axialdirection of the spiral tube portion 31.

[Initial Tension]

Now, the initial tension is described.

Under no load, the initial tension is the force which works in adirection to bring the wires 31 b of the closely wound portion 32 intoclose contact with each other in the axial direction of the closelywound portion 32. In other words, the initial tension is the force whichkeeps the closely wound portion 32 straight without flexing even ifexternal force (for example, gravity) is applied to the closely woundportion 32 in a no-load condition. Therefore, when external force isapplied to the closely wound portion 32 in the no-load condition, thewires 31 b are brought into close contact with each other in the axialdirection by the initial tension, and the closely wound portion 32 isnot flexed by the initial tension.

This initial tension is applied to the closely wound portion 32 from theside of the distal end portion 32 a of the closely wound portion 32 andthe side of the proximal end portion 32 b of the closely wound portion32 toward the center of the closely wound portion 32 along the axialdirection of the closely wound portion 32 as shown in FIG. 3A when theclosely wound portion 32 is formed. For example, the initial tension isapplied from the distal end portion 32 a to the proximal end portion 32b in the axial direction of the closely wound portion 32. Initialtension A in this case is, for example, 0N<A≦25N. This initial tensionof the closely wound portion 32 can be adjusted, for example, by awinding direction in which the wire 31 b is spirally wound.

As shown in FIG. 3A, for example, the initial tension is the force whichworks in a direction to bring the edges of the wires 31 b of the closelywound portion 32 into close contact with each other in a central axisdirection of the closely wound portion 32. In other words, when acentral axis of the closely wound portion 32 is, for example,horizontally placed, the initial tension is the force (preload) whichkeeps the edges of the wires 31 b of the closely wound portion 32 inclose contact with each other and keeps the closely wound portion 32difficult to bend and substantially straight against external force F(e.g., gravity). When the central axis of the closely wound portion 32is, for example, vertically placed, the initial tension is the force(preload) which keeps the edges of the wires 31 b of the closely woundportion 32 in close contact with each other against gravity and keeps nospace between the wires 31 b.

For example, as shown in FIG. 3A, suppose that the external force F isapplied to the central axis of the closely wound portion 32 when thecentral axis is, for example, horizontally placed. In this case, untilthe external force F reaches a force that cancels the initial tension,in other words, until the external force F surpasses the initialtension, no space is formed between the wires 31 b, and the closelywound portion 32 is not bent. On the other hand, when the external forceF applied to the central axis becomes equal to or more than the forcethat cancels the initial tension as shown in FIG. 3D, in other words,when the external force F surpasses the initial tension, a space isformed between the wires 31 b that have been in close contact, and theclosely wound portion 32 is bent. Therefore, the flexural rigidity ofthe spiral tube portion 31 is high because of the initial tensionapplied to the closely wound portion 32 until the closely wound portion32 starts bending. When the initial tension is canceled by the externalforce F and the closely wound portion 32 starts bending, the spiral tubeportion 31 bends in accordance with the spring constant of the spiraltube portion 31. Therefore, once the insertion portion 10 is insertedinto a body cavity (lumen) such as the large intestine and the closelywound portion 32 starts bending, the flexible tubular portion 25 can bebent as if the closely wound portion 32 were not present.

As shown in FIG. 3B, for example, a hook portion 35 is provided in theproximal end portion 32 b of the closely wound portion 32 to measure theinitial tension. A measuring instrument 37 such as a digital force gaugeis hooked to the hook portion 35. The distal end portion 32 a of theclosely wound portion 32 is fixed, and the measuring instrument 37 pullsthe closely wound portion 32 along the axial direction of the closelywound portion 32 via the hook portion 35. The measuring instrument 37measures the load when the closely wound portion 32 is pulled andstretched in the axial direction (when the wires 31 b are separated).The measured load is the initial tension.

A general spiral tube portion 131 is formed into the shape of asubstantially circular tube by molding a belt-shaped thin plate materialmade of, for example, a stainless steel material into a spiral shape, asshown in FIG. 3C. This spiral tube portion 131 is, for example, a thinmetallic spiral tube portion.

The spiral tube portion 131 is flexed by the application of the load ina diametrical direction of the spiral tube portion 131. In this case, inthe spiral tube portion 131, the load is proportional to the flexingamount (deformation amount), and the flexing amount is greater when theload is higher. With the same load, the flexing amount is greater whenthe rigidity of the spiral tube portion 131 is lower. In other words,with the same load, the flexing amount of a spiral tube portion 131 ahaving low rigidity is greater than the flexing amount of a spiral tubeportion 131 b having high rigidity, as shown in FIG. 4.

As shown in FIG. 3D and FIG. 4, the closely wound portion 32 is flexedfor the first time in accordance with the spring constant of the closelywound portion 32 when a load (hereinafter referred to as load A) equalto or more than the initial tension is applied to the closely woundportion 32. This load is, for example, an external pressure receivedfrom the intestines when the flexible tubular portion 25 is insertedinto the large intestine and abuts on a flection such as the sigmoidcolon of the large intestine.

The closely wound portion 32 according to the present embodiment has aspring constant lower than the rigidity of the spiral tube portion 131,and is flexed in accordance with this rigidity.

[Flexibility of Closely Wound Portion 32 and Spiral Tube Portion 131]

Now, the flexing of the closely wound portion 32 and the spiral tubeportion 131 is described in detail.

As described above and as shown in FIG. 3A and FIG. 4, the closely woundportion 32 is not flexed by the initial tension in the no-loadcondition. Moreover, as shown in FIG. 3A and FIG. 4, the wires 31 b arebrought into close contact by the initial tension, so that the closelywound portion 32 is not flexed even by the application of a load(hereinafter referred to as load B) equal to or less than the initialtension to the closely wound portion 32 in the diametrical direction ofthe closely wound portion 32. That is, the flexing amount is 0. Thus,the closely wound portion 32 keeps substantially straight in the no-loadcondition and under the load B.

As shown in FIG. 3D and FIG. 4, the wires 31 b are not separated eachother and the closely wound portion 32 is flexed for the first time whenthe load A is applied to the closely wound portion 32 in the diametricaldirection of the closely wound portion 32. That is, the flexing amountis equal to or more than 0. In other words, the closely wound portion 32is not flexed by the initial tension unless the load A is applied to theclosely wound portion 32.

When the load A is applied to the closely wound portion 32, the closelywound portion 32 is flexed in proportion to the spring constant of theclosely wound portion 32 lower than the rigidity of the spiral tubeportion 131, as shown in FIG. 4.

When the load is equal to or more than predetermined loads (hereinafterreferred to as loads C1 and C2) within the load A, the closely woundportion 32 is flexed more than the spiral tube portion 131 shown in FIG.3C under the same load. The load C2 is higher than the load C1.

For example, when a load equal to or more than the load C1 is applied tothe closely wound portion 32 and the spiral tube portion 131 b havinghigh rigidity, the closely wound portion 32 is flexed more than thespiral tube portion 131 b having high rigidity under the same load. Inother words, a load equal to or more than the load C1 is applied to theclosely wound portion 32 and the spiral tube portion 131 b having highrigidity, and the flexing amount of the closely wound portion 32 is thesame as the flexing amount of the spiral tube portion 131 b having highrigidity, in which case the load applied to the closely wound portion 32is lower than the load applied to the spiral tube portion 131 b havinghigh rigidity.

When, for example, a load equal to or more than the load C2 is appliedto the closely wound portion 32 and the spiral tube portion 131 a havinglow rigidity, the closely wound portion 32 is flexed more than thespiral tube portion 131 a having low rigidity under the same load. Inother words, a load equal to or more than the load C2 is applied to theclosely wound portion 32 and the spiral tube portion 131 a having lowrigidity, and the flexing amount of the closely wound portion 32 is thesame as the flexing amount of the spiral tube portion 131 a having lowrigidity, in which case the load applied to the closely wound portion 32is lower than the load applied to the spiral tube portion 131 a havinglow rigidity.

In the present embodiment, when a load equal to or more than the initialtension and equal to or less than the load C2 is applied to the closelywound portion 32, an operating force amount at the hand side istransmitted to the distal end portion side of the flexible tubularportion 25, and the closely wound portion 32 is slightly flexed to adegree enough for the flexible tubular portion 25 to be easily insertedinto the body cavity.

Although the flexing of the closely wound portion 32 has been describedabove, the same also applies to the flexing of the flexible tubularportion 25 having,the closely wound portion 32.

The closely wound portion 32 is formed, for example, by a metal such asSUS304. The cross-section of the wire 31 b of the closely wound portion32 is, for example, rectangular, as shown in FIG. 2 and FIG. 3A. In thiscase, the four corners of the wire 31 b preferably have a slightchamfered portion. A diameter of the closely wound portion 32 is, forexample, 10 mm, and a thickness of the wire 31 b in the closely woundportion 32 is, for example, 0.3 mm. The cross-sections of the wires 31 bof the closely wound portion 32 in the diametrical direction of theclosely wound portion 32 have the same length.

As shown in FIG. 2 and FIG. 3A, the closely wound portion 32 is formedso that the wires 31 b adjacent in the axial direction of the spiraltube portion 31 are brought into close contact with each other withoutspace therebetween by the above-mentioned initial tension. That is, inthe closely wound portion 32, the wires 31 b are in contact with eachother in the axial direction of the spiral tube portion 31.

As shown in FIG. 2, the sparsely wound portion 33 is formed so that thewires 31 b are provided apart from each other in the axial direction ofthe spiral tube portion 31 to have space in the axial direction of thespiral tube portion 31. That is, in the sparsely wound portion 33, thewires 31 b are not in contact with each other in the axial direction ofthe spiral tube portion 31.

As shown in FIG. 2, in the present embodiment, the sparsely woundportions 33 are provided in the distal end portion 31 g including thedistal end of the spiral tube portion 31 (the flexible tubular portion25), and the proximal end portion 31 h including the proximal end of thespiral tube portion 31 (the flexible tubular portion 25), as describedabove. One sparsely wound portion 33 a provided at the distal end iscoupled to the bending portion 23, and the other sparsely wound portion33 b provided at the proximal end is coupled to the main body portion61.

Here, L4=L1+L2+L3   Equation (1)

wherein in the axial direction of the straight spiral tube portion 31,the length of the central axis of the closely wound portion 32 is L1,the length of the central axis of the one sparsely wound portion 33 a isL2, the length of the central axis of the other sparsely wound portion33 b is L3, and the length of the central axis of the spiral tubeportion 31 is L4, as shown in FIG. 5A.

In general, the length of the central axis of the outer tube 51 isinvariable and remains the same whether the outer tube 51 is straight orbent. Therefore, the length of the central axis of the spiral tubeportion 31 covered by the outer tube 51 also needs to be invariable andremain the same whether the spiral tube portion 31 is straight or bent.

As shown in FIG. 5B, if the spiral tube portion 31 is bent, the wires 31b provided on the central axis of the closely wound portion 32 arefarther from each other than when the closely wound portion 32 isstraight. Accordingly, the length of the central axis of the closelywound portion 32 increases ΔT1. That is, when the spiral tube portion 31is bent, the length of the central axis of the closely wound portion 32is L1+ΔT1.

If the condition remains the same, the length of the central axis of thespiral tube portion 31 varies by ΔT1 between the straight and bentstates of the spiral tube portion 31. However, in the presentembodiment, the sparsely wound portions 33 are provided.

As shown in FIG. 5B, when the spiral tube portion 31 is bent, the wires31 b provided on the central axis of the one sparsely wound portion 33 aare closer to each other than when the one sparsely wound portion 33 ais straight. In other words, in the one sparsely wound portion 33 a, thespace between the wires 31 b is smaller. Thus, the length of the centralaxis of the one sparsely wound portion 33 a is ΔT2 smaller than when theone sparsely wound portion 33 a is straight. That is, when the spiraltube portion 31 is bent, the length of the central axis of the onesparsely wound portion 33 a is L2−ΔT2.

As shown in FIG. 5B, when the spiral tube portion 31 is bent, the wires31 b of the sparsely wound portion 33 provided on the central axis ofthe other sparsely wound portion 33 b are closer to each other than whenthe other sparsely wound portion 33 b is straight. In other words, inthe other sparsely wound portion 33 b, the space between the wires 31 bis smaller. Thus, the length of the central axis of the other sparselywound portion 33 b is ΔT3 smaller than when the other sparsely woundportion 33 b is straight. That is, when the spiral tube portion 31 isbent, the length of the central axis of the other sparsely wound portion33 b is L3−ΔT3.

Here, L5=L1+ΔT1+L2−ΔT2+L3−ΔT3   Equation (2)

wherein the length of the central axis of the bent spiral tube portion31 is L5, as shown in FIG. 5B.

Here, as described above, the length of the central axis of the spiraltube portion 31 needs to be invariable and remain the same whether thespiral tube portion 31 is straight or bent.

That is, it is necessary that L4=L5   Equation (3).

If Equations (1) and (2) are substituted for Equation (3),L1+L2+L3=L1+ΔT1+L2−ΔT2+L3−ΔT3, so that

ΔT1=ΔT2+ΔT3   Equation (4).

To put Equation (4) in other words, the stretch amount of the closelywound portion 32=the contraction amount of the one sparsely woundportion 33 a+the contraction amount of the other sparsely wound portion33 b.

Thus, the stretch amount of the closely wound portion 32 is equal to thetotal of the contraction amounts of the sparsely wound portions 33, andthe sparsely wound portions 33 contract as much as the stretch amount ofthe closely wound portion 32. That is, the sparsely wound portion 33absorbs the stretch of the central axis of the spiral tube portion 31associated with the stretch of the central axis of the closely woundportion 32 in the axial direction of the spiral tube portion 31 when theflexible tubular portion 25 is bent. In other words, the sparsely woundportion 33 offsets the stretch of the central axis of the spiral tubeportion 31. As a result, the sparsely wound portion 33 can smoothly bendthe flexible tubular portion 25 so that the characteristics of theclosely wound portion 32 are maintained.

[Mesh Tube Portion 41]

The mesh tube portion 41 is formed by, for example, a bundle ofstainless steel wires woven into the shape of a circular tube. In themesh tube portion 41, the wires are crossed and in the form of alattice.

[Outer Tube 51]

The outer tube 51 is formed by a flexible resin material such as arubber material into the shape of a circular tube to cover the outsideof the mesh tube portion 41.

[Operation Method]

Now, an operation method according to the present embodiment isdescribed.

As shown in FIG. 2, the spiral tube portion 31 has the closely woundportion 32 to which the initial tension is applied, and the sparselywound portions 33. The flexible tubular portion 25 has such a spiraltube portion 31.

Thus, when the straight flexible tubular portion 25 is inserted into abody cavity, the flexible tubular portion 25 keeps straight withoutflexing even if a load equal to or less than the initial tension, thatis, the load B is applied to the flexible tubular portion 25, as shownin FIG. 4. As a result, the flexing amount becomes 0, the operatingforce amount at the hand side is transmitted to the distal end portion(the distal end portion 31 g of the spiral tube portion 31) side of theflexible tubular portion 25, and the flexible tubular portion 25 is moreeasily inserted into the body cavity. That is, the flexible tubularportion 25 can be kept straight under the load B and is inserted intothe body cavity without flexing.

Even if load equal to or more than the initial tension and equal to orless than the load C1 is applied to the flexible tubular portion 25, theflexible tubular portion 25 flexes less than the flexible tubularportion having the spiral tube portion 131. Thus, the operating forceamount at the hand side is transmitted to the distal end portion side ofthe flexible tubular portion 25 as compared to the flexible tubularportion having the spiral tube portion 131, and the flexible tubularportion 25 is more easily inserted into the body cavity.

When the flexible tubular portion 25 is inserted in the body cavity andflexes by the load equal to or more than the initial tension and equalto or less than the load C1, load (e.g., the load C2) equal to or morethan the load C1 is additionally applied to the flexible tubular portion25, so that the flexing flexible tubular portion 25 is flexed more thanthe flexible tubular portion having the spiral tube portion 131 b, asshown in FIG. 4.

When the flexible tubular portion 25 is inserted in the body cavity andflexed by the load equal to or more than the initial tension and equalto or less than the load C2, a load equal to or more than the load C2 isadditionally applied to the flexible tubular portion 25, so that theflexing flexible tubular portion 25 is flexed more than the flexibletubular portion having the spiral tube portion 131 a, as shown in FIG.4.

Thus, when the already flexing flexible tubular portion 25 is furtherflexed in the body cavity under the load equal to or more than the loadC2, the flexible tubular portion 25 having the closely wound portion 32does not apply strong tension to the intestines under the same load evenif the flexible tubular portion 25 abuts on the flection of the largeintestine, so that no burden is imposed on the patient. Moreover, theflexible tubular portion 25 having the closely wound portion 32 isflexed more than the flexible tubular portion having the spiral tubeportion 131. At the same time, the flexible tubular portion 25 havingthe closely wound portion 32 is flexed by less load than the flexibletubular portion having the spiral tube portion 131 with the same flexingamount. In this way, the operation of the flexible tubular portion 25 iseasier.

When the flexible tubular portion 25 is flexed, the sparsely woundportion 33 absorbs the stretch of the central axis of the spiral tubeportion 31 associated with the stretch of the central axis of theclosely wound portion 32 in the axial direction of the spiral tubeportion 31. As a result, the flexible tubular portion 25 is smoothlyflexed by the sparsely wound portion 33 so that the characteristics ofthe closely wound portion 32 are maintained.

[Advantageous Effects]

As described above, according to the present embodiment, the spiral tubeportion 31 has the closely wound portion 32 to which the initial tensionis applied. Thus, according to the present embodiment, the flexingamount of the flexible tubular portion 25 can be 0 or smaller even if aload is applied to the straight flexible tubular portion 25. If a loadis further applied to the flexing flexible tubular portion 25, theflexing amount of the flexible tubular portion 25 can be greater.

According to the present embodiment, the straight or slightly flexingflexible tubular portion 25 can be easily inserted into the body cavity.Thus, according to the present embodiment, the operating force amount atthe hand side can be positively and easily transmitted to the distal endportion side of the flexible tubular portion 25, and the flexibletubular portion 25 can be more easily inserted into the body cavity.

According to the present embodiment, the flexible tubular portion 25does not need to strongly abut on the flection of the large intestine toincrease the flexing amount. In the body cavity, strong tension is notapplied to the intestines, and no burden is imposed on the patient.According to the present embodiment, the operation of the flexibletubular portion 25 can be easier.

According to the present embodiment, the initial tension is applied tothe closely wound portion 32 when the closely wound portion 32 isformed. Thus, according to the present embodiment, the initial tensionis not applied after the closely wound portion 32 and the flexibletubular portion 25 have been manufactured. Therefore, the time in themanufacture of the closely wound portion 32 and the flexible tubularportion 25 can be reduced.

According to the present embodiment, as shown in FIG. 5B, when theflexible tubular portion 25 is bent, the sparsely wound portion 33absorbs the stretch of the central axis of the spiral tube portion 31associated with the stretch of the central axis of the closely woundportion 32 in the axial direction of the spiral tube portion 31. Thus,according to the present embodiment, the flexible tubular portion 25 canbe smoothly bent so that the characteristics of the closely woundportion 32 are maintained by the sparsely wound portion 33.

According to the present embodiment, the sparsely wound portion 33 isadjoined to the closely wound portion 32. Thus, according to the presentembodiment, the stretch of the closely wound portion 32 can beimmediately absorbed by the sparsely wound portion 33.

According to the present embodiment, as shown in FIG. 2, the sparselywound portions 33 are provided in the distal end portion 31 g includingthe distal end of the spiral tube portion 31 (the flexible tubularportion 25), and the proximal end portion 31 h including the proximalend of the spiral tube portion 31 (the flexible tubular portion 25).Thus, according to the present embodiment, the influence of the stretchof the closely wound portion 32 on the bending portion 23 can beprevented by the one sparsely wound portion 33 a, and the influence ofthe stretch of the closely wound portion 32 on the main body portion 61can be prevented by the other sparsely wound portion 33 b.

According to the present embodiment, as shown in FIG. 2, the sparselywound portions 33 are provided in both ends of the closely wound portion32. However, the positions of the sparsely wound portions 33 do not needto be limited thereto. The sparsely wound portion 33 has only to beprovided at least at one end of the closely wound portion 32.

According to the present embodiment, as shown in FIG. 2, in the axialdirection of the spiral tube portion 31, the spiral tube portion 31 hasthe sparsely wound portion 33 a, the closely wound portion 32, and thesparsely wound portion 33 b in order from the distal end portion 31 g ofthe spiral tube portion 31 (the flexible tubular portion 25) to theproximal end portion 31 h of the spiral tube portion 31 (the flexibletubular portion 25). However, the arrangement of the closely woundportion 32 and the sparsely wound portions 33 does not need to belimited thereto.

As in a first modification of the arrangement of the closely woundportions 32 and the sparsely wound portions 33 shown in FIG. 6A, thespiral tube portion 31 may have, for example, the sparsely wound portion33, the closely wound portion 32, the sparsely wound portion 33, and theclosely wound portion 32 in order from the distal end portion 31 g ofthe spiral tube portion 31 (the flexible tubular portion 25) to theproximal end portion 31 h of the spiral tube portion 31 (the flexibletubular portion 25) in the axial direction of the spiral tube portion31.

As in a second modification of the arrangement of the closely woundportions 32 and the sparsely wound portions 33 shown in FIG. 6B, thespiral tube portion 31 may have, for example, the sparsely wound portion33, the closely wound portion 32, the sparsely wound portion 33, theclosely wound portion 32, and the sparsely wound portion 33 in orderfrom the distal end portion 31 g of the spiral tube portion 31 (theflexible tubular portion 25) to the proximal end portion 31 h of thespiral tube portion 31 (the flexible tubular portion 25) in the axialdirection of the spiral tube portion 31.

Thus, the closely wound portion 32 and the sparsely wound portion 33have only to be alternately provided along the axial direction of thespiral tube portion 31. In this case, the sparsely wound portions 33 andthe closely wound portions 32 are not particularly limited in number ifalternately provided. Thus, according to the present embodiment, theclosely wound portions 32 are provided in a wide range. Therefore, theflexible tubular portion 25 can be more flexibly bent, and the bendingdegree of the flexible tubular portion 25 can be adjusted.

As shown in FIG. 2, the sparsely wound portions 33 are provided in thedistal end portion 31 g including the distal end of the spiral tubeportion 31 (the flexible tubular portion 25), and the proximal endportion 31 h including the proximal end of the spiral tube portion 31(the flexible tubular portion 25). However, the sparsely wound portions33 do not need to be limited thereto. The sparsely wound portion 33 hasonly to be provided at least at one of the distal end portion 31 g ofthe spiral tube portion 31 and the proximal end portion 31 h of thespiral tube portion 31. Thus, the flexible tubular portion 25 has thesparsely wound portion 33 provided at least at one of the distal endportion 31 g and the proximal end portion 31 h of the spiral tubeportion 31.

The flexible tubular portion 25 according to the present embodiment hasthe spiral tube portion 31 (the closely wound portion 32 and thesparsely wound portion 33), the mesh tube portion 41, and the outer tube51, and has a three-layer structure. However, the structure of theflexible tubular portion 25 does not need to be limited thereto. Theflexible tubular portion 25 has only to have at least, for example, theclosely wound portion 32 to the whole of which the initial tension isapplied, and the sparsely wound portion 33.

According to the present embodiment, the initial tension is applied tothe whole of the closely wound portion 32. However, the initial tensiondoes not need to be limited thereto. The initial tension may be appliedto at least a part of the closely wound portion 32. The spiral tubeportion 31 may have the closely wound portion 32 to at least a part ofwhich the initial tension is applied, and the sparsely wound portion 33.The flexible tubular portion 25 has only to have at least such a spiraltube portion 31.

According to the present embodiment, the initial tension is continuouslyapplied from the distal end portion 32 a to the proximal end portion 32b. However, the initial tension does not need to be limited thereto. Forexample, the initial tension may be applied to the distal end portion 32a and the proximal end portion 32 b, and does not have to be applied tothe part between the distal end portion 32 a and the proximal endportion 32 b. Thus, the initial tension may be discontinuously applied.In this case, each initial tension is, for example, substantially thesame.

The magnitude of the initial tension according to the present embodimentmay change in the axial direction of the closely wound portion 32. Forexample, the initial tension applied to the side of the proximal endportion 32 b of the closely wound portion 32 is greater than the initialtension applied to the side of the distal end portion 32 a. In thiscase, the initial tension is smaller from the side of the distal endportion 32 a of the closely wound portion 32 to a desired part on theside of the proximal end portion 32 b of the closely wound portion 32,and is greater from the desired part to the proximal end portion 32 b ofthe closely wound portion 32. Alternatively, the initial tension maygradually increase continuously from the side of the distal end portion32 a toward the side of the proximal end portion 32 b.

Thus, the side of the distal end portion 32 a is formed as a softportion, and the rigidity on the side of the distal end portion 32 a islow. The side of the proximal end portion 32 b is formed as a hardportion, and the rigidity on the side of the proximal end portion 32 bis high.

Thus, according to the present embodiment, the side of the distal endportion 32 a is formed as the soft portion. Consequently, the side ofthe distal end portion 32 a can be inserted along the intestines withoutapplying strong tension to the intestines even if the side of the distalend portion 32 a abuts on the flection of the large intestine. The sideof the distal end portion 32 a can be easily inserted into the bodycavity, and the burden on the patient can be reduced.

According to the present embodiment, the side of the proximal endportion 32 b is formed as the hard portion. Consequently, even if theoperating force amount at the hand side is applied to the flexibletubular portion 25, that is, even if the operator applies force (load)to the flexible tubular portion 25, the flexible tubular portion 25 canbe prevented from being easily flexed, the operating force amount at thehand side can be easily transmitted to the distal end portion 32 a, andthe flexible tubular portion 25 can be easily inserted into the bodycavity.

According to the present embodiment, the advantageous effects describedabove can be obtained as along as the initial tension is only applied tothe side of the proximal end portion 32 b. In this case, for example,when the initial tension is not applied to the distal end portion 32 aand is applied to the side of the proximal end portion 32 b, themagnitude of the initial tension applied to the side of the proximal endportion 32 b may be uniform in the whole of the side of the proximal endportion 32 b, or may gradually increase toward the proximal end portion32 b.

As described above, the initial tension may be discontinuously applied.In this case, the initial tension applied to the side of the distal endportion 32 a is lower than the initial tension applied to the side ofthe proximal end portion 32 b. Moreover, the magnitude of the initialtension applied to the side of the distal end portion 32 a graduallyincreases toward the proximal end portion 32 b as described above, andthe initial tension applied to the side of the proximal end portion 32 bgradually increases toward the proximal end portion 32 b as describedabove. In this case, the highest initial tension applied to the side ofthe distal end portion 32 a is, for example, lower than the lowestinitial tension applied to the side of the proximal end portion 32 b.

Thus, the magnitude of the initial tension is the same or varies in theaxial direction of the closely wound portion 32. In other words, therespective closely wound portions 32 have uniform initial tension ordifferent initial tensions. Thus, according to the present embodiment,the hardness or resilient force of the flexible tubular portion 25 canbe freely adjusted to the use of the flexible tubular portion 25, andthe operability of the flexible tubular portion 25 can be freelyadjusted.

The above-mentioned change of the initial tension may be applied to oneclosely wound portion 32 as shown in FIG. 6A, or may be applied to morethan one closely wound portion 32 as shown in FIG. 6B. When more thanone closely wound portion 32 is provided, the initial tension applied tothe closely wound portion 32 on the side of the distal end portion 31 gmay be the same as or different from the initial tension applied to theclosely wound portion 32 on the side of the proximal end portion 31 h.When the initial tension varies, the initial tension may graduallyincrease from the distal end portion 32 a of the closely wound portion32 on the side of the distal end portion 31 g toward the proximal endportion 32 b of the closely wound portion 32 on the side of the proximalend portion 31 h. Thus, the application of the initial tension is notparticularly limited as long as the initial tension is applied to atleast a part of the closely wound portion 32.

Thus, according to the present embodiment, as shown in FIG. 2, thecross-sections of the wires 31 b of the closely wound portion 32 havethe same length in the axial direction of the closely wound portion 32,but the present invention does not need to be limited thereto. Forexample, the cross-sectional shape of the wire 31 b of the closely woundportion 32 in the axial direction of the closely wound portion 32 maychange in the axial direction of the closely wound portion 32. Thischange shows that, for example, at least one of the thickness of thewire 31 b corresponding to the length of the diametrical direction ofthe wire 31 b and the length corresponding to the width of the wire 31 bchanges in the axial direction of the closely wound portion 32. Thischange means that, for example, the width of the closely wound portion32 provided on the side of the distal end portion 31 g of the spiraltube portion 31 is shorter than the width of the closely wound portion32 provided on the side of the proximal end portion 31 h of the spiraltube portion 31. This change also means that, for example, in oneclosely wound portion 32, the width on the side of the distal endportion 31 g is shorter than the width on the side of the proximal endportion 31 h. Thus, according to the present embodiment, the flexibletubular portion 25 can be more flexibly bent, and the bending degree ofthe flexible tubular portion 25 can be adjusted. Therefore, in thecross-section of the wire 31 b of the closely wound portion 32, thelength of in the cross-section in the axial direction of the closelywound portion 32 may be the same or vary.

According to the present embodiment, the number of turns of the closelywound portion 32 may change. For example, as shown in FIG. 6C, thenumber of turns of a closely wound portion 321 a provided on the side ofthe distal end portion 31 g of the spiral tube portion 31 is 3, thenumber of turns of a closely wound portion 321 b provided closer to theside of the proximal end portion 31 h of the spiral tube portion 31 thanthe closely wound portion 321 a is 5, and the number of turns of aclosely wound portion 321 c provided closer to the side of the proximalend portion 31 h of the spiral tube portion 31 than the closely woundportion 321 b is 7. The change of the number of turns is substantiallysimilar to the above-mentioned change of the initial tension.

Thus, according to the present embodiment, the flexibility of the spiraltube portion 31 can be changed, the degree of freedom of flexibility canbe improved, and the flexible tubular portion 25 having diverseflexibilities can be provided.

Although the number of turns of the closely wound portion 32 changesaccording to the present embodiment, the present invention does not needto be limited thereto. The number of turns of the sparsely wound portion33 may change. Thus, the number of turns of at least one of the closelywound portion 32 and the sparsely wound portion 33 may change in theaxial direction.

According to the present embodiment, the present invention does not needto be limited to the above as long as the flexibility of the spiral tubeportion 31 can be changed. For example, the outside diameter of theclosely wound portion 32 may change. For example, the outside diameterof the closely wound portion 321 b is greater than the outside diameterof the closely wound portion 321 a, and the outside diameter of theclosely wound portion 321 c is greater than the outside diameter of theclosely wound portion 321 b. For example, the outside diameter of theclosely wound portion 321 a may change in such a way as to increase fromthe distal end portion 31 g toward the proximal end portion 31 h in theaxial direction of the spiral tube portion 31. The variation of theoutside diameter is substantially similar to the above-mentioned changeof the initial tension.

Although the outside diameter of the closely wound portion 32 changesaccording to the present embodiment, the present invention does not needto be limited thereto, and the outside diameter of the sparsely woundportion 33 may change. Thus, the outside diameter of at least one of theclosely wound portion 32 and the sparsely wound portion 33 may change inthe axial direction of the spiral tube portion 31.

According to the present embodiment, the cross-section of the wire 31 bof the closely wound portion 32 may have an oval shape as a firstmodification of the cross-sectional shape of the wire 31 b of theclosely wound portion 32 shown in FIG. 7A. Thus, in the presentmodification, the section of the wire 31 b is R-shaped. Therefore, thewinding angle at which the wire 31 b is spirally wound can be obtuse ascompared to the case where the section is rectangular. Thus, accordingto the present embodiment, a higher initial tension can be applied tothe closely wound portion 32. Moreover, in the present modification, thecross-section has the oval shape, so that the wires 31 b are in pointcontact with each other, and the area of contact between the wires 31 bis smaller. Thus, in the present modification, the friction between thewires 31 b is reduced, and the closely wound portion 32 can be smoothlybent.

According to the present embodiment, as in a second modification of thecross-sectional shape of the wire 31 b of the closely wound portion 32shown in FIG. 7B, the cross-section of the wire 31 b of the closelywound portion 32 may have a circular shape. Thus, in the presentmodification, the cross-section of the wire 31 b has no edge, so that itis possible to prevent the wires 31 b from running on each other in thediametrical direction when the wires 31 b are curved into the R-shapehaving a low curvature.

According to the present embodiment, as in a third modification of thesectional shape of the wire 31 b of the closely wound portion 32 shownin FIG. 7C, the cross-section of the wire 31 b of the closely woundportion 32 may have an elliptic shape. Thus, in the presentmodification, it is possible to improve the resistance of the wire 31 bto collapse without increasing the size of the wire 31 b in itsdiametrical direction.

In view of the above, the cross-section of the wire 31 b of the closelywound portion 32 may have, for example, at least one of the rectangularshape, the oval shape, the circular shape, and the elliptic shape.

In this case, when the section of the wire 31 b has one of therectangular shape, the oval shape, and the elliptic shape, theabove-mentioned length of the cross-section in the axial direction ofthe closely wound portion 32 means at least one of the lengthcorresponding to the thickness of the wire 31 b and the lengthcorresponding to, for example, the width of the wire 31 b in the closelywound portion 32 as described above. When the cross-section of the wire31 b has the circular shape, the above-mentioned length of the sectionin the axial direction of the closely wound portion 32 means, forexample, the diameter of the wire 31 b.

The endoscope 1 may be used for medical purposes or industrial purposes.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventiveconcept as defined by the appended claims and their equivalents.

What is claimed is:
 1. A flexible tubular portion of an endoscopeincluding a spiral tube portion, wherein the spiral tube portioncomprising: a closely wound portion to at least a part of which aninitial tension is applied, and a sparsely wound portion provided atleast at one end of the closely wound portion.
 2. The flexible tubularportion of the endoscope according to claim 1, wherein the closely woundportion and the sparsely wound portion are alternately provided along aaxial direction of the spiral tube portion.
 3. The flexible tubularportion of the endoscope according to claim 2, wherein the number ofturns of at least one of the closely wound portion and the sparselywound portion is configured to change in the axial direction.
 4. Theflexible tubular portion of the endoscope according to claim 1, whereinthe outside diameter of at least one of the closely wound portion andthe sparsely wound portion is configured to change in the axialdirection.
 5. The flexible tubular portion of the endoscope according toclaim 1, wherein the sparsely wound portion is provided at least at oneof a distal end of the spiral tube portion and a proximal end of thespiral tube portion.
 6. The flexible tubular portion of the endoscopeaccording to claim 1, wherein the magnitude of the initial tension isconfigured to change in a axial direction of the closely wound portion.7. The flexible tubular portion of the endoscope according to claim 1,wherein the cross-sectional shape of a wire of the closely wound portionin a axial direction of the closely wound portion is configured tochange in the axial direction of the closely wound portion.
 8. Theflexible tubular portion of the endoscope according to claim 1, whereina wire of the closely wound portion has at least one of a rectangularshape, an oval shape, a circular shape, and an elliptic shape.
 9. Anendoscope comprising the flexible tubular portion of the endoscopeaccording to claim 1.